My husband and I are planning to buy an old Cape Cod 1.5 story style New England Farmhouse in Maine in a couple of years. The home we are buying has a fieldstone foundation with a mud cellar and we want to change it to a full two story by changing the pitch of the gable roof from 12/12 to 7/12 which should (if my geometry is correct) give us 8' ceilings all the way across. The house is balloon framed and I would like to know how we should go about extending the walls once we change the pitch of the roof. On the current "second" floor the eve side walls are approximately 30-36" on the interior finished side.

What is the safest and most structurally sound way to do what we want?

I know when we go do actually do the project we will have to have an architect and/or a structural engineer draw up plans.

The second part is about the foundation. I want to add head room to the cellar. The current cellar gets a couple of inches of water during spring and heavy rains, but it drains through the floor and the current owner has added a sump pump. With a fieldstone foundation, can we dig out the current mud floor (about a foot and a half of depth) and concrete the floor without harming the current fieldstone walls? The cellar is for mechanical only and will never be a living or storage space.

nkelly wrote:What is the safest and most structurally sound way to do what we want?

I know when we go do actually do the project we will have to have an architect and/or a structural engineer draw up plans.

That is your answer right there.

Too many unknowns and missing information to attempt to advise otherwise.

The same for the cellar because you would need to stay clear of the existing foundation walls - I would not proceed any further without deciding on a architect and engineer (many architects have engineers on staff or with whom they work)

It already floods ... yet you want to dig it deeper?

Doing as much renovation as you are describing, I would raise the entire house up a few feet, fill in the cellar to above the highest flood level, pour concrete foundation walls, or at a minimum use concrete block (formed and poured foundation walls would be better than concrete block).

Start with an architect, otherwise you may well come up with a design you want which is not practical to construct - the architect can start you on the correct path and guide you around many stumbling blocks you may otherwise become quite personally acquainted with - in a bad way.

In addition to the above, the existing field stone foundation wall could be left in place and serve as a decorative exterior wall surface (cladding) to the exterior of a concrete foundation wall, or could serve as a decorative interior surface for the concrete foundation wall.

Raising the entire house to a sufficient height to provide for drainage below a floor would create a lower usable story to the house. Raising houses is done in preparation to move or relocate a house to another lot, or to raise a house above flood elevation, so doing so is not all that uncommon. Raising your house would be equivalent to raising it above flood elevation.